The following invention relates to a steering drive for a motor vehicle for boosting the steering thrust, which comprises a belt drive.
Steering drives, which support the handling of the steering wheel and simplify the vehicular steering for the driver are frequently used in motor vehicles. The German patent publication DE 10 2004 059 A1 reveals such a steering drive. In the case of this steering drive, the electric motor required for boosting the steering thrust is disposed parallel to the steering column of the steering drive in order to save installation space. The disposal of the electric motor laterally to the steering column is also known from prior art. This arrangement requires more installation space in comparison to the parallel arrangement.
The electric motor of the aforementioned publication interacts with the steering column by means of a belt drive. In the case of this arrangement, the operating speed required for boosting the steering thrust is however very high so that the noise emissions by said electric motor are also very high. Furthermore, the tensile load on the shaft of the electric motor due to the belt is very large, which leads to a bowing of the rotor under load and causes additional noise generation.
In addition, steering drives for luxury-class vehicles require a very large assistance torque at a simultaneous high level of efficiency in order to load the on-board power supply system as little as possible. A belt drive of the kind mentioned in the aforementioned publication has however the advantage of loading the on-board power supply system only to a small extent on account of a high degree of efficiency of the arrangement. Nevertheless, a large assistance torque like that required for steering drives in luxury-class vehicles is very difficult to transfer or cannot be transferred at all via the steering column.